That's only the name of the software running the instance. Each instance would have a more accessible name, like carboot.uk, yardsale.us, etc. I currently tell people to go and sign up with feddit.uk or lemm.ee, not vaguely point them at Lemmy.
If anyone asked what 'flohmarkt" meant, you tell them "flea market" and, at least for English speakers, I expect them to go "oh yeah, I see it now" and go about their day, slightly the wiser.